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Choosing The Best Pump for Your WaterCooling System

If you already have a good understanding of centrifugal pumps, but want to learn more, please read this PDF located HERE

My Recomendations!
There are the pumps I reccomend. I am reccomending these pumps off of the calculations that cathar did. I will link you to those right here.

DDC-2/MCP355 DDC-1/MCP350- Any incredibly popular pump all over the world for its small size and excellent performance, the DDC-2 provides performance exceeding the AQX50Z and MCP655, while having a smaller footprint and consuming the same power as the MCP655 (the AQX50Z consumes less than half). Please read more on this pump further down in the guide and in the links provided. (Note: the DDC-2 with and without modified tops is not included in the calculations that Cathar made due to the fact that they were released after the calculations were published, but Alex "Petra" has created detailed PQ curves of the various DDC models which are linked below in the DDC Section)

AQX50Z- My second recomendation is the mcp600 or aqua extreme50z. They are the same pump as I explain further down in my guide. This pump provides the most head pressure between the D4 and itself and will also give you the best temps. Should be noted that the DDC has higher max head but is 3/8 and will provide less flow. Surprisingly enough, when this pump is run at 13.8 volts it will beat pretty much any pump on the market. It is only beaten by running two of them in series. It is quite amazing only drawing 8 watts of power. this really is the ultimate water cooling pump. Low power, high head, and great temps. Its only downside is that it is not as long lasting as some of the others. I have no real data on how long it will run for, but suffice to say that the iwaki will outilve it by a while.

MCP655- My third recomendation is the D5/MCP655. It is a bit more powerful than the AQX50Z, but dumps appx 2 times the heat into the water. With this in mind, the MCP655 is an excelent choice for those with more powerful radiators. for users with a single 120mm fan radiator the 50Z would be the better option, but larger radiators will be able to handle the heat.

Iwaki MD20RLZ- My fourth reccomendation is the Iwaki MD20RZ. The MD20RLT will also work, providing temps roughly .1 c higher. This pump is incredibly powerful and is a balance between power and heat generation. Please take notice. If you are looking for a quiet/silent pump, the MD20 is NOT what you are looking for, but if you are in the market for an ac pump it is the only way to go.

Extreme Pumps:
There is really only one company that makes the more extreme end of pumps that water coolers generally use. Those are iwakis. I use one and can attest to their greatness. You cannot purchase them at comp mod places such as danger den, frozen cpu or crazypc, but you can get them from www.customaquatic.com . They seem to have the best prices on them.
There are 4 models that I have seen people use. That is the RD30, MD-15, the MD-20, and the MD-30. NOTE: get the RL or RLZ and NOT the RLX, as the RL and RLZ has much more head height than the LX. They are the ones that we want to use. There are also American and Japanese versions. The Japanese versions are supposed to be better, but cost 50 percent more money. The main difference between the American and Japanese ones is size and noise level. The Japanese based Iwakis are both smaller and quieter. If u got the cash to pay for the Japanese ones go ahead. For the 20 and 30 series there are the RLZ. These are versions with different impellers and have even higher pressure and head than the RLT's. I didnt put them in the main section becuase i forgot to (sorry). The RZT series would be a better choice for those running restrictive systems.

UPDATE:After some research on the flow curves of the Iwakis i found that at 2.5gallons per minute of flow then the Z series and the L series of pumps will have the exact same pressure characteristics. If your loop will obtain a higher gpm than 2.5gpm then the L series will be beneficial, and if your flow will be below 2.5gpm then the Z series will be more benefical to your system. Surprisingly enough 2.5gpm is actually attainable with an iwaki md20rlt or rzt. Even with a dual heatercore rad, res, and cpu block you can acchieve around 2.8gpm with a tdx cpu block. around 2.3 gallons per minute if you are running with the number 4 insert. These numbers are based off of the iwaki md20. Running with the Storm block roughly 2.1 gpm is attainable with the same setup.

RD30:
This is the absolute pincale of performance. This pump is a 24volt DC pump that has incredible head pressure, amazing flow, and relatively low heat dump. I dont have exact numbers, but I will ask around and get some solid numbers on the pq curve. I know of two ppl using this pump, one of them being cathar, and the other Niksub1 (who got it for cathar if im not mistaken). Now I would have put this pump in my reccomendations at the top of the page, but the price of it would make anyone but the most xtreme of xtremes gasp in shock. The price on one of these monsters is 275 dollars. Now you also need to get a 24volt power supply. A variable power supply is reccomended as these pumps seem to give the best heat/power ratio when run at 18 volts according to Niksub1 and Cathar. The price on a 24volt power supply is in the range of 50-100 dollars for good one as far as i know. I will have a link up as to where to get them later on, as i cant seem to find it right now.

MD-15: - I removed the info on this pump as there is ABSOLUTELY NO REASON TO BUY THIS PUMP.

MD-20/WMD-20This pump based off of cathars calculations is the best AC based pump that money can buy. It will give you the lowest temperatures regardless of setup (given that you have a dual fan rad or more).
This is the bigger brother of the MD-15. This pump does 6.7gallons per minute and has 14 feet of head. This is where Iwaki goes into a class of its own. There are no other aquarium pumps that can touch these. (I'm sure there are some out there somewhere, but for the most part...) This pump can handle literally anything you can throw at it. I had to retighten all my seals on the water block to get it watertight again. As far as noise goes, this pump is very quiet with respect to its power output. It does have some noise on the lower hertz which will be noticeable unless you put the pump in some kind of soundproof enclouser. That said, I DO NOT reccomend this pump for anyone going for a silent rig as they will be sorely disapointed with the noise level. This pump is inteded for those where noise is not all that much of a concern and performance is the main goal. This model is 110 dollars for the WMD (American) and 160 for the MD (Japanese) model. This pump consumes rougly 45 watts of power, and dumps 14.5-20 watts of heat into the water.

MD-30RLT/WMD-30RLTNOTE: Cathars recent test data show that this pump is rather useless due to the high heat output (50 watts). In light of this information, this pump will actually give you higher overall temperuates, regardless of radiator (even up to 2 3fan rads) and even with a gpu attached. So please do not get this pump. You will be wasting your money!
This pump is for those who have more money than they know what to do with and want to test how well they can seal their system from leaks. I only know of one person who owns one. Cathar... If your reading this you might not know him, but he is the inventor of the whitewater, cascade, and storm blocks. He doesn’t even use this pump in his system, just uses it for testing (cathar correct me if I’m wrong). This pump is basically the bigger brother of the MD-20RLT. Its specs are 8.5gallons per minute, and 17.7 feet of head. In other words u can have this pump on the first floor of your house and have the computer on the second floor if u want to. The price on this model is 125 for the WMD (American) model and 209 for the MD (Japanese) model. If anyone has any more info they want to add, just pm me. This pump consumes roughly 50 watts of power, making it useless in water cooling setup s due to the amount of heat that it puts into the loop.

BlueLine/Panworld
These pumps are very similar to the Iwakis. The head of the company of Blueline was previously the head engineer over at Iwaki. He branched off and started his own company Blueline. These pumps are very comparable to the Iwakis in performance and have similar part numbers (makes it easy to compare). As welll they are a little cheaper. All of there pumps can be boughten at Aquadirect and they even have a comparison of the equivalent Iwaki pumps. Upon further inspection the prices on these pumps are exactly the same as the American Iwaki's. So its really a tossup. I know of a few people over here at xtremesystems who use these pumps and they swear by them. So quality is not an issue. It should be noted that of the Bluelines they do not seem to have a "high head" model like the Iwaki Z series. But in the same respect the Z series are like urban legends in and of themselves.

12volt Pumps:

Laing DDc-1/DDC-2/MCP350/MCP355
The Laing DDC (MCP350) and DDC-2 (MCP355) are two excelent pumps. Stock, they come with 3/8" barbs, but that is easily changed with tops from companies like Petra's tech shop (my first reccomendation) and Alphacool. the DDC-1 consumes 9 watts of power and is virtually silent when mounted on foam/gel or suspended with rubber bands of some sort. The DDC-2, which has become wildly popular in recent months, consumes 18watts and is only marginally louder (still quieter than all other 12v and Extreme pumps listed in this guide). My reccomendation to you is that you seriously consider the DDC-2 (with the 1/2" barbs) if you have a system that has a dual 120mm rad or larger. The DDC or AQX50Z listed below for those of you with smaller radiators. There is one potential downside to the DDC. It appears that there have been numerous failures of the pump after appx 1week to 2months of use. The pump is under warranty, and there do not seem to be that many failures (percentage wise), but I feel obligated to provide all information. For more complete information on this pump and performance comparisons check out these threads. Performance Comparison of DDC-2 with 1/2" tops, More Petra'sTech DDC Pump Testing and eXa's Guide to DDC Names and Specs

AquaExtreme 50Z / MCP600 Rev2.0This pump is actually better than the lainD4. I will say that right off the bat. Here is why. 1.It has more head pressure 2. Its cheaper. If you are in the market for a pump and dont want to spend the extra dough on an iwaki pump this IS the pump to get. and if you want a little lower temps go with 2 of them in series. This setup cannot be beat. It will give you approximately the same temps as running a iwaki md20RZ.
This pump was the previous version of the 12v pump that swiftech carried. They no longer carry it due to supply line issues, but it is a good pump. The rev 1 version had reliability issues with the impeller, but that is fixed now. The pump is called the 50Z and can be boughten at CoolTechnica. This particular pump is not nearly as popular as the Laing D4's now, but I have heard reports that head to head, this pump will sometimes outperform the d4 in high pressure systems. Note that I do not have any hard proof of this (I am working on that), but there are reports. The specs are 3gallons per minute and 10.5 feet of head, with 1/2inch barbed fittings. The price is around 80 dollars over at cooltechnica. It sucks about 7 watts of power

MCP655 (D5)
This is the newly released laing pump that offers a considerable improvement over the previous D4. (April 2005 release date). Some of the imrpovements include reduced noise (D4 has a horrible whinning noise, though some say it is not noticeable), input all the way up to 24volts so you can overvolt it ALOT without voiding the warranty.(NOTE: Anything above ~12.8volts does not net more performance but rather just increases heat output and is not suggested to be overvolted above 12.8volts) The other feature that is noteable is the adjustable dial on the back of the pump that allows you to adjust the speed of the pump down when maximum performance is not needed. The power consumption of this pump is 24 watts and heatt dump is reported to be 18watts like the DDC-2. The maximum head pressure is 13.8 feet and maximum flow is 5.2gpm. The price is 75 dollars.

Laing D4 - Pump out of production - No longer reccomendedThis is a great little pump that is marketed by danger den and swiftech. It replaced the mcp600 because of failures with the pump. But that is now fixed. It is actually weaker and more expensive than the mcp600, but it does improve on the operational life of the mcp600. So if you are going to have you pump for a very long time this might be a better choice. Other than that, the pump really does not provide the value and performance that the mcp600 does. it can be had over at www.dangerden.com under the name of d4. This pump costs 75 dollars. It sucks about about 15 watts of power

AC Pumps:
There are really only 2 choices of pumps that people are using, and thus I will not comment on any others. The Mag 3,5,or7 is one of these pumps. Please stay away from these pumps, as they are made to be submersed and are highly prone to leaking. If you insist on getting one please be sure to seal up the pump with some plumbers goop, or silicone sealer. Failure to do so could result in a very dead computer.

Hydor L35
This is a good inexpensive 120volt AC pump. I have heard many people have great success with this pump. There is also a L30 and L20, but with the L35 coming onto the market I wont talk about them, as you would most likely choose the mower powerful L35 over the other two. Its not as popular as some of the other pumps, but its a good pump. The price is around 50 dollars and it does 5.3 gallons per minute. It has a maximum head pressure of 6.83 feet and consumes 21watts. I should report that I have heard some not so great things about the reliability of this pump, and know of an alarmingly high number of RMA's. With that said, if you can afford to get a better pump do so. But if you dont have the money for a better pump, the L35 should be fine.

Eheim 1048
Eheim makes very good pumps and this pump is no exception. Many people used this pump before the D4 came out and many still do. Although it is not very powerful compared to other pumps, it is small, quiet, and highly reliable. I do not pump recommend this pump for restrictive systems with the new water blocks. If you have a less restrictive system and do not plan to do extreme over clocking then this pump will be fine. It pumps 2.63 gallons per minute and 4ft 11inches of head. It costs 49 dollars over and danger den.

Eheim 1250
This is the more commonly used Eheim pump. Again, like its little brother, it is highly reliable, wont leak, and quiet. It is a little bit bigger than the 1048. If you want specs on its exact size check out http://www.eheim.com . It pumps 4.4gallons per minute at 6ft 7inches of head. It costs 59 dollars over at danger den. I would recommend this pump to pretty much anyone who doesn’t want a 12v dc pump and wants a good reliable pump. This pump is still not the most powerful one out there, but it should work fine in most cases, except the more extreme systems that are more restrictive, or have allot of components. You can still use it with restrictive blocks and while using allot of components, but I would only recommend this if you do not plan to over clock to the max of the system, or if you plan to make a more silent system.

If anyone has ANYTHING they want to add please do not hesitate to pm me. If you think that any part of my post is biased or just incorrect, please let me know and I can change it to be more fair to all products.

Please do not Flame me for anything you don’t agree with. Just let me know and I can correct my post, given that you are correct.

I want a bit more performance than the l30. I shoudl have mentioned that Im going for max perforance on this. Im going to have a black ice extreme 2, danger den TDX and a maze4 for the gpu. All running on tygong 1/2inch id.

Dark hacker, (or anyone else) are the black ice extremes not high performing radiators. From what I have seen they are very good performers. Correct me if im wrong. As far as heatercores what would i get.

Would that dual heatercore be equivalent to the one over at voyeur mods? Its a bit cheaper, and it would be one less place to buy stuff from as I am alredy ordering alot from Danger den.

My budget just went up a bit. Well rather realocated itself as I no longer need to bother with the BIX and can get a heater core. Now i can spend about 120 on a pump and still be under budget. Time to look at the iwaki's

EDIT:
I was looking at the Iwaki pumps and I found their "low end" model and it has some pretty good specs on it. My question is if I will need to get adapters to fit 1/2inch ID tubbing on it. If so can somone help me with what I would need? Here is a link to it

I found the hose diamiters on it. one is 5/8 and the other is 3/4. Danger den sells a 5 dollar kit to reduce 5/8 to 1/2 but they dont have one for 3/4. I would think the 5/8 reducer woudl be fine for the 3/4. Let me know if im crazy.

i got the Iwaki MD-15R ..havn't fully tested it yet since im building my WC for my A64 rig atm now too... i should have it ready for its first test by next week or so. But remember they aren't submersible, they are not suction pumps, & they are heavy and big ...which is good try find the iwaki's with barbs already ...i got the threaded version too ...and finding barbs that fit was a pain ...plus makes the pump even bigger.

i also got the eheim 1250 in my P4 rig, i love that too simply cuz it runs in all conditions ....submersible, its a suction pump and simply never dies (i had it run dry for a while by mistake and nothing).

As far as Iwakis go, I dont have the money for the japanese made ones. I would need to get the american made ones. Is there that much of a difference. It seems unlikely that the american made one is that much worse than the japanese one. On the websites they said that the japaense motor is just quieter. I can deal with a slightly noisier motor if that is the main difference.

Originally posted by MaxxxRacer As far as Iwakis go, I dont have the money for the japanese made ones. I would need to get the american made ones. Is there that much of a difference. It seems unlikely that the american made one is that much worse than the japanese one. On the websites they said that the japaense motor is just quieter. I can deal with a slightly noisier motor if that is the main difference.

you can often get iwakis cheap on ebay...
these are both very nice pumps @60hz...

I'll just go with the american made iwaki. I want to get this setup as soon as possible. Dont want to deal with ebay. Im more than confident that the american made iwaki will still bet the hell out of any hydor ehiem or the swiftec pump.

My power supply cnat handle 2 of those pumps. Im on a 350 watt enermax. Ironicly though its 12v power rail is twice that of cheap 450watt psus. But still. I dont feel like frying my power supply.

to be perfectly clear. I have a 450watt cheap psu in my room. It puts out 17amps on the 12v line. My 350watt psu puts out 26amps on the 12v line. I think enermax was insanely conservative in their ratings.

Originally posted by MaxxxRacer My power supply cnat handle 2 of those pumps. Im on a 350 watt enermax. Ironicly though its 12v power rail is twice that of cheap 450watt psus. But still. I dont feel like frying my power supply.

to be perfectly clear. I have a 450watt cheap psu in my room. It puts out 17amps on the 12v line. My 350watt psu puts out 26amps on the 12v line. I think enermax was insanely conservative in their ratings.

i reckon your PSU could handle it (they don't draw much) ... but the downside is that a pair of them costs $160+

the american iwakis are fine - i have a pair of wmd-30RZs myself.... (bought on the recommendation of a guy on OCAU who'd owned both types)

@a5h - yes all the iwakis 15 and below only come with japanese motors...

Yeah, that is a tad bit too expensive. The single iwaki 20 will have more power and flow than to of the swiftecs and it costs less and is less of a hassle to tube. The only problem i will face is getting the 1/2 tubbing over the 3/4 barbs i had to get for the iwaki pump. The aquairim place didnt have 3/4 to 1/2 reduce barbs with female threads.

Any suggestions on how to get the tubing over the 3/4 barbs. I heard one guy ran boiling watter and quikcly dunked the tubing in and then put it over the barb. So that it got it a little soft and then it just reshaped the tubbing. would this be a good or bad idea?

why dont you just get the barbs off the internet at say www.mcmaster.com they will definatly have them. even if you do boil the tubing i dout you can get it to strech 1/4in especially with thich walled tubing

I love mcmaster. Those dudes got everything. there is litteraly no piece of hardware those guys dont cary. Its the scarriest thing. Have you ever seen one of their catalog books. It makes the websters unabrigged dictionary seem like a pocket organizer.

EDIT: Marine depot (where im ordering the pump from) told me which parts i need to order from their site to get my system running. A sum total of 7 dollars worht of fittings and barbs. Not bad if u think about it. A bit easier for me. Mcmaster rocks but I like to keep my orders and grouped (not ordering from 5 places) as possible. Thanks for the help though. Now all that is left to order my system. That will be done in an hour or so.